Metal cans and glass jars being heat resistant, can both be used for heat processed, wet-pack foods and for non-heat treated dry pack canning. For wet foods, however, metal cans have several disadvantages for the do-it-yourselfer. They are hard to come by, and they take specialized equipment to use that can be difficult to locate. Probably the greatest flaw which makes them unpopular for home canning heat processed wet-pack food is that they can only be used once. Since the commercial canning industry is not interested in reusing the containers, metal cans make great sense for their purposes. The cans are both cheaper (for them) and lighter than glass jars. This adds to the economy of scale that makes canned foods as cheap as they are in the grocery store.
For home canning, wet-pack heat processed foods glass jars are better because even the smallest of towns will usually have at least one business that carries pressure and boiling water canners along with jars, rings and lids. With metal cans a can sealer is necessary and this usually has to be ordered from the manufacturer or a mail-order distributor. A few of which are listed in the Resources section.
Metal cans are not really made entirely of tin. They're actually steel cans with a tin coating on the inside and outside. Some kinds of strongly colored acidic foods will fade in color from long exposure to tin so a type of enamel liner called "R-enamel" is used to forestall this. Certain other kinds of food that are high in sulfur or that are close to neutral in pH will also discolor from prolonged contact with tin. For those foods, cans with "C-enamel" are used.
The excellent food preservation book, Putting Food By Chapter 6 (see reference list) has a section on the use of metal cans for wet packed foods.
It is in dry-pack canning that metal cans for home use begin to come into their own. Because microbiological sterilization isn't necessary, foods that are dry packed into containers do not have to be subjected to heat processing nor does the safety of their seals depend upon the vacuum that the cooling contents create. This means that other packaging methods and container types may be used.
Probably the most common use of metal containers is the #10 cans such as are used by the LDS family canneries discussed below. This is not the only way they may be used though. It will probably take a bit of searching, but there are various food grade metal containers available of sufficient volume to make them useful for food storage. They usually have double friction lids similar to paint cans or screw caps like jars that can achieve an air-tight seal. If you can find them in a large enough volume capacity they can be of real use for storing bulky foods such as grains, legumes and sugar. Smaller cans of a gallon or less would be useful for storing items like dry milks. If properly sealed, metal cans have a far higher barrier resistance to gasses such as oxygen, CO2, and nitrogen than any plastic, assuming there in no lining performed with .
Although they can hardly be considered portable the use of metal drums (not garbage or trash cans), either themselves food grade or used with food grade liners, is also a possibility. A fifty five gallon drum full of grain will weigh several hundred pounds, but may make for a much easier storage solution than multiple buckets. The advantage of using such a large container is that a great amount of a single product can be kept in a smaller amount of space. The disadvantages are the difficulties of moving it and rotating the stock in the drum, which is critical for food usage and to reduce spoilage. Just be sure to use in individual that are labeled properly with the date. You will also need to be careful about moving a mylar bag full of food as the sides can tear in the process. But, in the end it may make more sense to store your food in .